|  | 1.2 | The Physical Layer of the OSI Reference Model
| 1.2.1 | Three categories of Ethernet

Together, Ethernet and IEEE 802.3 currently maintain the greatest share of any local-area network (LAN) protocol used. Today, the term Ethernet is often used to refer to all carrier sense multiple access collision detect (CSMA/CD) LANs that generally conform to Ethernet specifications, including IEEE 802.3. When it was developed, Ethernet was designed to fill the middle ground between long-distance, low-speed networks and specialized, computer room networks carrying data at high speeds for very limited distances. Ethernet is good for applications where a local communication medium must carry sporadic, occasionally heavy traffic at high-peak data rates. The term Ethernet refers to the family of LAN implementations that includes three principal categories: Ethernet and IEEE 802.3--LAN specifications, which operate at 10 Mbps over coaxial and twisted-pair cable. 100-Mbps Ethernet--A single LAN specification, also known as Fast Ethernet, which operates at 100 Mbps over twisted-pair cable. 1000-Mbps Ethernet--A single LAN specification, also known as Gigabit Ethernet, which operates at 1000 Mbps (1 Gbps) over fiber and twisted-pair cables. Ethernet has survived as an essential media technology because of its tremendous flexibility and because it is simple to implement and understand. Although other technologies have been promoted as likely replacements, network managers have turned to Ethernet and its derivatives as effective solutions for a range of campus implementation requirements. To resolve Ethernet's limitations, creative users (and standards organizations) have created bigger and bigger Ethernet pipes. Critics might dismiss Ethernet as a technology that cannot grow, but its underlying transmission scheme continues to be one of the principal means of transporting data for contemporary campus applications.
| Web Links
| Ethernet Technologies
| Spurgeon's Ethernet Site
| Lower OSI Layers